1. Field of the Invention
The present invention relates to a multifunction trainer.
2. Description of Related Art
A power bender is a device for training forearms. Typically a bower bender includes a shelled spring and two handles for being held by an operator, and the two handles are respectively arranged at the left side and the right side of the shelled spring.
The conventional method to assemble the spring and one of the two handles is firstly to put an iron tube into an end of the spring, where the outer diameter of the iron tube is greater than the internal diameter of the spring. After that, an end of the iron tube is plugged with a lock nut. A screw is then screwed with the lock nut. And finally the screw is screwed with one of the two handles.
Because the operation of the power bender frequently needs bending and shocking, the iron tube easily detaches from the spring. Some manufacturers weld the iron tube with the spring to keep them fixed. However, the spring may become fragile after the thermal welding process.